1. Field of the Invention
The present invention relates to a drive unit for driving a fuel pump for a small-sized vehicle using an electronic control unit (ECU).
2. Description of Background Art
A conceptual view of a drive unit for driving a fuel pump for a motorcycle is shown in FIG. 6. Referring to FIG. 6, gasoline is fed from a fuel tank 2 into a fuel pump 4 through a filter 3. The gasoline is pressurized in the fuel pump 4, and is fed into a fuel injector 6 through a filter 5.
The fuel pressure in an intake manifold 7 is maintained constant by a pressure regulator 8, and gasoline is fed into the fuel tank 2 through the pressure regulator 8, thus gasoline can circulate back to the fuel tank 2. A piston 21 is reciprocated along with the combustion of gasoline, to rotate a crank (not shown).
A power supply voltage is supplied from an on-vehicle battery 10 to the fuel pump 4. The fuel injection amount of the fuel injector 6 is controlled by an ECU (Electronic Control Unit) 9.
In the related art for motorcycles, the fuel pump 4 is driven such that a flow rate of gasoline passing through the fuel pump 4 is maximized irrespective of the fuel injection amount of the fuel injector 6.
In the case where a total current consumption of an electric system is large as in a four-wheeled vehicle, a ratio of the current consumption of the fuel pump to the total current consumption of the electric system becomes small.
Meanwhile, in the case where a total current consumption of an electric system is small, as in a motorcycle, a ratio of the current consumption of the fuel pump to the total current consumption of the electric system becomes large.
For this reason, it is expected to develop a drive unit for driving a fuel pump for a motorcycle, which is capable of reducing the current consumption of the fuel pump.
Further, it is expected to develop a drive unit for driving the fuel pump for a motorcycle, which prevents an injection amount of a fuel injector from being varied depending on a change in the power supply voltage of the fuel pump.
According to the present invention, a drive unit for driving a fuel pump for a small-sized vehicle is provided wherein an electronic control unit drives the fuel pump on the basis of control data for controlling the fuel injection amount of the fuel injector and of the power supply voltage applied to the fuel pump.
Since the drive of the fuel pump is controlled on the basis of control data of the injection amount of the fuel injector and of the power supply voltage of the fuel pump, the drive of the fuel pump can be controlled such that the drive power of the fuel pump is reduced in the case where the fuel injection amount is small.
The drive of the fuel pump can also be controlled such that the fuel injection amount (or injection pressure) is prevented from becoming deficient depending on a change in power supply voltage of the fuel pump.
According to the present invention, a drive unit for driving a fuel pump for a small-sized vehicle is provided wherein an electronic control unit drives the fuel pump under pulse-width modulation (PWM) using a PWM signal on the basis of control data for controlling a fuel injection amount of the fuel injector and of a power supply voltage applied to said fuel pump in such a manner that a pulse-width of the PWM signal is made larger with an increase in the fuel injection amount of said fuel injector and is made smaller with a decrease in the fuel injection amount of the fuel injector.
Since the drive of the fuel pump is controlled on the basis of the control data of an injection amount of the fuel injector and of a power supply voltage of the fuel pump, the drive of the fuel pump can be controlled such that the drive power of the fuel pump is reduced in the case where the fuel injection amount is small.
The drive of the fuel pump can also be controlled such that the. fuel injection amount (or injection pressure) is prevented from becoming deficient depending on a change in the power supply voltage of the fuel pump.
For example, the drive unit is configured wherein a pulse-width of a PWM signal is made larger with an increase in the fuel injection amount of the fuel injector so that the fuel pump can be driven at the maximum flow rate when the pulse-width is maximized. Further, the pulse-width of the PWM signal is made smaller with a decrease in the fuel injection amount of the fuel injector so that the power consumption of the fuel pump can be reduced when the fuel injection amount is small.
According to the present invention, a drive unit for driving a fuel pump for a small-sized vehicle is provided wherein the electronic control unit drives the fuel pump under pulse-width modulation (PWM) using a PWM signal on the basis of control data for controlling the fuel injection amount of said fuel injector and of the power supply voltage applied to said fuel pump in such a manner that when the power supply voltage of said fuel pump is larger than a rating voltage, a pulse-width of the PWM signal is made smaller than that in the case where the power supply voltage is equal to the rating voltage; and when the power supply voltage of said fuel pump is smaller than the rating voltage, the pulse-width of the PWM signal is made larger than that in the case where the power supply voltage is equal to the rating voltage.
Since the drive of the fuel pump is controlled on the basis of the control data of the injection amount of the fuel injector and of a power supply voltage of the fuel pump, the drive of the fuel pump can be controlled such that the drive power of the fuel pump is reduced in the case where the fuel injection amount is small.
The drive of the fuel pump can also be controlled such that the fuel injection amount (or injection pressure) is prevented from becoming deficient depending on a change in the power supply voltage of the fuel pump.
For example, when the power supply voltage of the fuel pump is larger than a rating voltage, the drive power of the fuel pump can be lowered and thereby the power consumption thereof can be reduced by reducing the pulse width of a PWM signal as compared to the case where the power supply voltage of the fuel pump is equal to the rating voltage.
Similarly, when the power supply voltage of the fuel pump is smaller than the rating voltage, the fuel injection amount (or injection pressure) can be prevented from becoming deficient depending on a change in the power supply voltage of the fuel pump by increasing the pulse-width of the PWM signal as compared to the case where the power supply voltage of the fuel pump is equal to the rating voltage.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.